Transformer



S. E. JOHANNESEN. I

TRANSFORMER.

APPLICA I ,1.9H. 1,331,068. Patented Feb. 17,1920.

Inventor:

Svend E..Johannesen,

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TRANSFORIVIER.

Specification of Letters Patent.

Patented ee. 17, teen Application filed March 6, 1917. Serial No. 152,561.

To all whom it may concern:

' Be it known that I, SVEND E. J OHA N-, NESE'N, a citizen of the United States, resid- .ing at Pittsfiel-d, in the county of Berkshire,

State of:Massachusetts, have invented certain neW and JuSefuI Improvements in Transformers, of which the following is a specification.

My invention has for its object the provision of a transformer having good electrical properties and in which the materials, and particularly the windings, are/advantageously arranged.

I have shown my invention embodied in a type oftransformer similar to that shown in patent to Hall #861,029, particularly as regards the form of the core which is provided with a middle leg the ends of which are connected by a plurality of outer legs which complete the magnetic path of the middle leg and which are spaced therefrom to form an annular space within which the primtry and secondary windings are dispose It is common practice in building up the windings of a transformer to segregate, more or less, the primary and secondary windings, and it has hitherto been proposed to build up the windings of a transformer having a core of the form above indicated, by interposing, radially, a primary winding between an outer and an inner secondary winding' It is well known that, other things being equal, the better the primary and secondary windings are intermixed, the lower will be the reactance of the transformer, and inasmuch as the windings of sulating spacing member.

the transformer just referred to are well intermixed, the same has a low reactance.

But while such an arrangement of the windings is satisfactory as. regards the reactance of the transformer, it is unsatisfactory from the standpoint of the best utilization of the winding space, since the two insulating spacing members which it is necessary to provide between the primary winding and the two secondary windings occupy just so much valuable winding space. It has also been proposed'to form the windings ofasingle primary anda single secondary winding separated by a cylindrical in- While such an arrangement well utilizes the winding space, the transformer has an undesirably high reactance, since the windings are 4 poorly intermixed.

"In accordance with my invention, I utillze the winding space to good advantage by providing a single primary winding separated from a single secondary winding,

by'a single insulating spacing. Instead,

however, of providing plain cylindrical windings with a plain cylindrical insulating space or member between the two as has hitherto been the common practice, I rnest one winding within the other, so that a section of the insulating space between the two concentric windings formed by a plane passing through the axis of thetransformer instead of being bounded by straight lines at its sides, gives atrace having the appearanceof a distorted curve. Thereby. a good intermixing of the windings is produced,

and hence a low reactance; at the same time, there is but a slngle lnsulating space,

and while it occupies more space than.

would a cylindrical insulating space of the same thickness, it is'but little more and I have found that the gain effected in the lowering of the reactance much more than compensates for the slight loss in winding space due to the increase of the length of the cross section of the insulating space.

For a fuller understanding of my invention, reference may be had to the accompanying drawing showing several modified forms thereof, and in which:

Figure l is a perspective view of a transformer embodylng my invention with the windings partially broken away;

Fig. 2 is aside view showing one of the legs ofthe core of the transformer, with the windings in section; and

Figs. 3, 4 and 5 are views similar to Fig. 2 showing modified forms of my invention.

Referring now to the drawings, and first to Figs. 1 and 2, in which I'have shown what I at-present consider the preferred form of my invention, 10 is a core of a transformer similar to that shown in the Hall patent above referred to, and which is rovided with a restricted middle leg not shown in the drawing) formed from one of the sides of each of a number of laminated units such as shown in Fig. 2. The outer legs 10 '10, 10 and 10 of the units are spaced, fronr-the middle leg to form anannular winding space 11 in which the priprimary winding adjacent the secondary winding presents a convex appearance while the adjacent side of the secondary winding is concave, the two being separated by an insulating member, 14, the cross section of which determined by a plane passing through .the axis of the transformer as shown in Fig. 2 is curved as shown. In this manner, as will be obvious, the windings are well intermixed and therefore the transformer has a low reactance; at the same time the winding space is utilized to good-aidvantage. The primary and secondary windings are insulated from the core of the transformer by a member 15.

Fig. 3 shows a modified form of my invention in which the nesting of the windings is effected, by making one Winding, here shown as the primary winding 12 T- shaped in cross section, and providing two distinct secondary windings 13". on either side of the stemof the T.

Fig. l shows another modified form of my invention in. which the primary winding 12 is rectangular in cross section and is nested within'a U-shaped secondary winding 13, which incloses the primary winding on three sides.

Fig. 5 shows still another form of my invention in which a single primary winding 12. is nested within two secondary windings, 13, the primary and secondary being separated by an lnsulatmg member made up in cross section: by twa straight members extending obliquely from the ends of the winding space to the middle of, one ot the sides.

While l have illustrated my invention in connection with a particular form of tlfi11 former, it will, of course, beunderstood that it is not limited thereto in its application,

but may advantageously be used in connec tion with any transformer.

In accordance with the provisions of the' the invention can be carried out by other means. What I claim as new and desire to secure by Letters Patent of the United States is:

In a transformer, the combination with a distributed core having a restricted middle leg, of concentric exteriorly cylindrical primary and secondary windings surrounding said leg, and an insulating member separating said primary and secondary windings into intermingledportions in a predetermined fashion whereby the trace of said member'in a plane containing the trans former axis is a distorted curve.

In witness whereof, I have hereunto set my hand this 27th day of Feb, 1917.

' SVEND E. JQHANNESEN. 

